Fluid flow switch and method of making the same



Dec. 18, m4. F, Moos 11,984,419

FLUID FLOW SWITCH AND METHOD OF MAKING THE SAME Filed March 10, 1932 2Sheets-Sheet 1 Dec. 18, 1934. F. Moos I FLUID FLOW SWITCH AND METHOD OFMAKING THE SAME Filed March 10, 1932 2 Sheets-Sheet 2 ATTORNEY two fluidbodies.

Patented Dec. 18, 1934 UNITED STATES PATENT OFFICE FLUID FLOW SWITCH ANDMETHOD OF MAKING THE SAME Application March 10, 1932, Serial No. 593,019

14 Claims.

The present invention relates to fluid flow switches, and to the methodof making the same.

The invention consists in a novel fluid flow switch, and in the methodof making the same, as hereinafter set forth and claimed.

A particular object of the invention is to provide a fluid flow switchwhich will inherently make and break an electric circuit between fluidpools, regardless of how said switch is handled between said operations.Another object of the invention is to provide a switch of the tiltingtype which will operate equally well at any rotational position of saidswitch. A further object of the invention is to provide a switch having'ahigh current rupturing capacity. Still another object of the inventionis to provide a switch of simple and inexpensive construction embodyingthe foregoing features. Another object of the invention is to provide anexceptionally compact switch, devoid of cups and similar protuberances.Another object of the invention isv to provide a novel method ofproducing such a device. Still other objects and advantages of theinvention will appear from the following detailed specification, or froman inspection of the accompanying drawings.

Fluid flow switches are of two general types; one the type in which afluid body moves into contact with a metallic electrode, and the otherthe type in which contact is made by merger of The latter type of switchhas an inherently greater current capacity, due both to the fact thatthe circuit is more effectively ruptured between fluid pools,,and to thefact that a better contact is formed at the instant when the circuit isclosed, with a consequent avoidance of the" arcing upon circuit closingwhich is so characteristic of the other type of switch, espe cially whenrelatively large currents are being controlled. As heretoforeconstructed, however, switches of the fluid merger type have had theundesirable feature that if improperly handled the circuit could beclosed through these switches by contact between the fluid and ametallic electrode, whereupon the switch would be destroyed by thelong-continued arc of make. I have now discovered that by a novelstructure of my invention all possibility of closing the circuit througha fluid flow switch except by the desired merger of the fluid poolsmaybe absolutely precluded, regardless of how the switch is handled. Infact. the mercury pools are so effectively maintained about the inleadsthat the switch may be operated through extreme angles, or evencontinuously rotated end over end, without ever making or breaking thecircuit except by the desired separation or merger of fluid pools.Moreover, my new switch may be operated with equal facility in anyrotational position, due to its symmetry. My novel switch is also ofextremely simple and inexpensive construction, especially when madeaccording to a novel process of my invention.

For the purpose of illustrating my invention I have shown a preferredform of my novel switch, together with several modifications thereof, inthe accompanying drawings, in which Fig. 1 is an elevational view of amercury switch in the closed circuit position,

Fig. 2 is an elevational view of the same switch ,in an open circuitposition,

Fig. 3 is a cross section of the same switch, taken on the line 33 ofFig. 1,

Fig. 4 is a longitudinal section of the same switch in another position,

Fig. 5 is a view similar to that of Fig. 4 of a slightly modifiedswitch,

Figs. 6 to 9 are elevations, in part section, of other modifications ofthe switch of Fig. 1, and

Figs. 10 and 11 are sectional view of another modification of the switchof Fig. 1.

In these drawings, with particular reference to Figs. 1-4, there isshown a switch having a tubular envelope 1 within which there is aconcentric tubular member 2. One end of said tubular member is fusedinto said envelope at the pinch seal 3, while the other end thereofterminates a short distance from the other end of said envelope 1. Theenvelope 1 can be of any suitable vitreous material, such as lead glass,lime glass, or the like, but Where relatively large currents are to beinterrupted I prefer to use a glass which is more resistant to heat,such as one of the borosilicate glasses of the type known to the tradeas Pyrex or Nonex. The tubular member 2 is preferably of the samematerial as the envelope 1, although it is obvious that a morerefractory material, such as fused silica, may be used therefor by theinterposition of a suitable graded joint between this member and saidenvelope, if desired. A thin metallic sleeve 4 closely fits the outsideof the tubular member 2, while a similar sleeve 5 closely fits theinside of said member, eachof said sleeves terminating an appreciabledistance from the open end of said tubular member 2. These sleeves,which serve as contact rings, may be of any metal which will notcontaminate the fluid. In a mercury switch I find it convenient to usecold rolled steel, for example, since due to its natural resilienceslitted sleeves made thereof can be relied upon to make the desired snugfit with said tubular member 2. Inleads 6 and 7 extend through saidpinch seal 3 and are welded to the sleeves 4 and 5 respectively. Whenthe inner sleeve 5 is formed of a fiat strip rolled up, as shown, an earon one end of this strip is preferably turned inward, and the inlead 7welded to the inturned end, since this allows said inlead 7 to bebrought nearer the center of the pinch seal 3 without bending saidinlead, allowing more space for the seal-ofi 8. The envelope 1 may beevacuated,- of course, through a centrally located tubulation,connecting with the inside of the tubular member 2, in which case thesealoff tip 8 will be between the inleads 6 and 7, making unnecessarythe off-setting of theinlead 7 with respect to the sleeve 5. I find,however, that the envelope 1 is more conveniently evacuated through atubulation connecting with the annular space between said envelope andthe tubular member 2, and hence prefer to use the structure shown.Sufficient mercury, or other electrically conducting fluid, 9 isenclosed within said envelope to extend an appreciable distanceabove'the open end of the member 2 when the switch is in the positionshown in Fig. 4, so, that it is in contact with the sleeves 4 and 5. Asuitable arc suppressing atmosphere,

v preferably hydrogen, is sealed within said envelope 1.

The manufacture of these switches is extreme- 1y simple and inexpensive,due to the novel arrangement of the parts thereof. According to thepreferred method the sleeves 4 and 5 are formed and the beaded inleads 6and 7 welded thereto. Said sleeves are then slipped over and insiderespectively an open ended vitreous tube which becomes the tubularmember 2. The envelope 1 is then placed over this assembly, with atubule extending into the space between said assembly and said envelope.The end of said envelope and the adjacent end of the tubular member 2are then heated and pinched down about the inleads 6 and 7, a singleoperation thus pinched down' on the inlead '7.

' the pinch seal 3 in two steps.

of the softened glass not to close the passage in the tubule. Severalways are now known of tubulating through a pinch seal, however, hencethe details thereof need not be discussed here. The switch is thenexhausted and the mercury and hydrogen admitted thereto in any suitablemanner, although I prefer to use the method .disclosed in Patent1,831,935, issued November 1'7, 1931, to Warren R. Walker. Thetubulation is then closed in a conventional manner, forming the seal-offtip 8.

In some cases it may be desirable to produce In this case the tubularmember 2 and the beaded inleads 6 and are assembled as before, and. themember 2 During this pinching the bead about the inlead 6 merges withtheglass at the pinchforming a unitary .assembly-.- The envelope is thenslipped over this assembly and fused thereto, after which the switch isfinished'according to the method hereinbefore described. With thismethod of construction the closed end of the tubular member 2 can bepositioned slightly away from the pinch seal 3, as shown in Fig. 5,giving a structure which has certain advantages, including greaterimmunity to temperature strains.

In operating either the switch of Figs. 1-4, or that shown in Fig. 5,the end of the envelope 1 cooperates with the closed tubular member 2 toform a trap for a pool of themercury 9. No matter how this switch isturned the member 2 will always scoop up and retain a predeterminedquantity 9 of mercury, as shown in Fig.2. This mercury 9 is sufficientin quantity to extend beyond the sleeve 5 toward the open end of thelining 2 whenever the switch approaches the circuit closing position, sothat the circuit is always closed by the merging of two fluid bodies.Likewise the relative positions of the electrodes and of the lining aresuch that whenever the mercury pool 9' has been merged with the mainbody of mercury 9 to close the circuit through the switch it isimpossible to move the mercury out of contact with either sleeve withoutfirst separating the mercury pools. Thus it is absolutely impossible toeither open or close a circuit through this switch, except by thedesired separation or merger of fluid pools. Moreover, the switchoperates with equal facility at any rotative position. As a result thisswitch is singularly immune to failures due either to faultyinstallation or faulty manipulation, and may be described as a foolproofswitch.

In some cases, as where particularly large currents are to beinterrupted, I find it desirable to cause the arc of rupture to occurfar ther inside of the tubular member 2 than is the case with the switchof Figs. 1-4. This may be easily accomplished in either of two ways. Asshown in Fig. 6 the open end of the tubular member 2 is flared out,causing the mercury pool 9 to recede farther into said member before itseparates from the main body of mercury 9. Or as an alternative the endportion of the tubular member 2" may be made of smaller diameter thanthat of the remainder of said memher, as shown in Fig. 7, thusfurnishing a ledge over which the mercury separates, causing the arc ofrupture to occur well within the tubular member. Either of thesealternatives obviously reduces the arcing against the end wall of theenvelope 1, and thereby tends to increase both the rupturing capacityand the useful life of the device.

In some cases it may be desirable to have a highly refractory tubularmember within an envelope of a less refractory material to which itcannot be directly sealed. Such a construction is shown in Fig. 8. Theenvelope 1 of this switch may consist of any vitreous material, as inthe switches previously described. The member 12, which is tubular withone end closed, is made of any desired refractory material, such aslavite, porcelain, fused silica, borosilicate glass, or the like. Theinlead 7 extends through a small hole in the closed end of said member12, and that portion of said lead which extends between said tubularmember 12 and the pinch seal 3 is preferably beaded, so that the switchmay be operated without regard to its rotative position. For

inlead and said lining have sufficiently similar coefficients ofexpansion. With this construction the lining 12 is wholly supported inthe desired concentric position by the sleeves 4 and 5, and by theassociated inleads 6 and 7. Where a soft glass is used for the envelope1, I flnd it desirable in some cases, especially where relatively largecurrents are to be interrupted, to provide a cup-shaped lining 14 ofmore refractory. material, such as that used for the tubular member 12,within the end of said envelope. Said lining 14 overlaps the end of themember 12 by an appreciable distance, and thus very effectively shieldsthe envelope 1 from any arcs of rupture. Any desired means may be usedto fix said lining 14 in position, but as shown-the inlead 6 has anextension 6' which is bent outwardly to engage said lining and firmlyhold it against the end of the envelope 1, while one or more outwardlyextending ears 15 on the sleeve 4 may also be used for the same purpose.With this construction all the inner parts of the switch are interlockedand firmly supported within the envelope 1, with the result that thisswitch is extremely rugged and resistant to shocks. The operation ofthis switch is identical with that of the switch of Figs. 1-4, and henceneed not be further described.

A modification of the switch of Fig. 8 is shown in Fig. 9. In thisswitch the open end of the tubular member 12 extends toward the pinchseal 3, while the closed end of said tubular member is against the otherend of the envelope 1. With this construction the inlead 7 extendsdirectly into the open end of said member 12, being beaded from thepinch seal to a point some distance inside of said shell 5, so as topermit operation of the switch in any rotative position. Thisconstruction permits of an easier assembly, and hence is somewhatcheaper to produce than the switch of Fig. 8. Such a switch operates inthe same manner as the other switches described, especially in thelarger sizes, where the inlead '7 does not appreciably impede the flowof the mercury 9 into the open end of the tubular member 12.

A further modification of my switch is shown in Fig. 10. The switchshown in this figure has a metal shell 21 substituted for the vitreousenvelope 1 of the switches of the previous figures. This metal shell,being conductive, also takes the place of the outer sleeve 4 and theinlead 6 of the other switches illustrated. Various modes ofconstruction may, of course, be used in carrying out my invention whileusing such a metal envelope, but the simple and. inexpensive form hereillustrated is preferred. With this construction a piece of tubing 22 ofany suitable vitreous material, having one end flared, has a sleeve 5fitted therein with the inlead 7 extending through the flared end. Atubule is then inserted within the flared end, after which the vitreoustube 22 is pinched down on said tubule and said lead to make a pinchseal 23 according to the conventional method used in making tiplesslamps. This assembly is then placed in the metal envelope or shell 21,and the flare of said tubing 22 is sealed thereto. The metal shell 21may be made of any desired metal which will not contaminate mercury byamalgamation therewith, and the tubing 22 may be of any material whichwill fuse to said shell without excessive strain. In practice, however,I find it desirable to form the shell 21 of either iron or a chrome-ironalloy, in which case the tubing 22 is preferably of either lead or limeglass, since either of these glasses seals readily and permanently toeither of these metals. The more refractory glasses, such asborosilicate glass, fused silica, and the like may, of course, be usedeither by making the envelope 21 of a metal, such as molybdenum, towhich they can be sealed, or through the interposition of a graded jointbetween the metal shell and the more refractory part of the tubularmember 22. Such a graded joint would preferably come at a point betweenthe pinch seal 23' and the open end of the tube. In order to minimizeany strains at the glass-to-metal seal the metal shell 21 is preferablymade rather thin at this point, thus reducing the amount of compressionwhich it can exert on the glass. The mode of operation of this switch isidentical with that of the switches previously described, connectionbeing made to the main body of mercury 9 either by inserting theenvelope 21 in a suitable contact making clip, or by means of a lead 6'welded or soldered thereto. This switch likewise has all the advantagesof the other switches, plus the advantages inherent in a metal envelope,such as increased heat radiation, with a consequent increased continuouscurrent carrying capacity, a marked lessening of the breakage hazard,omission of one inlead and the like.

In some cases it is desirable to retain the advantages, such as easymanipulation, obtained by using a soft glass for the tubular member 22,and at the same time to increase the current rupturing capacity of theswitch. A structure by which this is conveniently accomplished by asimple modification of the switch of Fig.- 10 is shown in Fig.11. Inthis modification a tubular lining member 24, of any suitable refractorymaterial, such as lavite, porcelain, fused silica, or the like, isslipped into the open end of the tubular member 22. The outer end ofsaid lining 24 has an outwardly extending flange 25 which engages theend of the tubular member 22, while the inner end of said lining has aninwardly extending flange 26. The metal sleeve 5 is fitted within saidlining 24 with one end against said flange 26, said lining being firmlyheld in place thereby. The frictional fit of the lining 24 in thetubular member 22 is usually adequate to prevent the formation of acurrent carrying mercury path therebetween, but if desired, packingmaterial, such as asbestos fiber or glass wool, may be interposedtherebetween; or the lining and the tubular member may be fused togetherto form a. ring seal therebetween. The latter operation can be easilycarried out, for example, where the lining 24 is of lavite and thetubing 22 is of soft glass, since these materials are readily sealed toeach other. In this switch the are always occurs on the refractorylining 24, with the result that very large currents can be interruptedwithout damage to the switch. In some cases I find it desirable to formthree or more projecting ears 27 on the aforesaid flange 25, said earsextending outwardly into contact with the envelope 21, and therebyforming a support for the open end of the tube 22. Said ears are equallyspaced and are made narrow enough not to impede free fiow of mercurythereby. With such a construction this switch is exceptionally rugged,and will withstand much abuse. While the use of ears on said flange, asdescribed, offers the most convenient method of producing the desiredresult, various other expedients, such as studs on the member 22, mayobviously be used, if desired, in lieu thereof.

The construction shown in any of these switches permits the handling ofrelatively large currents in a switch of small size and simpleconstruction. For example, a switch of the type shown in Fig. 1, havinga length of approximately one inch and a diameter of about of an inch,will safely carry and interrupt from 10 to 20 amperes at 110 volts D.C., if the en velope and lining are made of a borosilicate glass, suchas Nonex. Larger interrupting capacities may be easily obtained eitherby using a more refractory material, or by increasing the dimensions ofthe switch. The latter alternative also increases the continuous currentcarrying capacity as well, and hence is the more desirable solution inmost cases.

The construction disclosed in any of these switches is also singularlyrugged. In each of these constructions all of the component parts of theswitch cooperate with and mutually support each other, thus providing aswitch which can successfully withstand severe mechanical shocks andmishandling, either 'in transit, in

installation, or in actual operation.

While I have described my invention by reference to particularembodiments thereof it is to be understood that it is not limitedthereto, but that various changes, substitutions or omissions, withinthe scope of the appended claims,

may be made in the switches described, or in the method of manufacturethereof, without departing from the spirit of my invention. I claim asmy invention:-

1. A mercury switch comprising a sealed envelope of vitreous material,mercury therein, a concentric vitreous tube fused to said envelope atone end, the other end of saidtube approaching the opposite end of saidenvelope, an inlead extending into said envelope through the fusedportion of said envelope and tube and extending into said tube, saidinlead terminating in a thin shell closely fitting the interior of saidtube, and an inlead extending into the space between said tube and saidenvelope and terminating in a contact ring about said tube.

2. A mercury switch comprising a sealed tubular envelope, mercurytherein, a vitreous tube within said envelope, 'an inlead sealed intosaid envelope, said inlead terminating in a sleeve within said tube,said tube being supported by said sleeve, and means to make contact withthe mercury exterior to said tube.

3. A mercury switch comprising a sealed tubular envelope, mercury insaid envelope, a concentric vitreous tube within said envelope, one endof said tube being closed and the other end thereof approaching theopposite end of said envelope, an inlead sealed into said envelope, saidinlead terminating in a sleeve within said tube, said tube beingsupported by said sleeve, and an electrical conductor which makescontact with the mercury exterior to said tube whenever said switch isin such a position that said mercury extends within said tube.

4. A mercury switch comprising a sealed tubu lar envelope, mercurytherein, a concentric vitreous tube within said envelope, one end ofsaid tube being closed and the other end thereof approaching theopposite end of said envelope, two inleads sealed into said envelope,one of said inleads extending into said tube and being insulated fromcontact with the mercury exterior thereto, said inlead terminating in athin sleeve within said tube, the other inlead extending into the spacebetween said tube and said envelope and carrying a sleeve which extendsabout said tube, said tube being supported by said sleeves, and an arcsuppressing atmosphere within said envelope.

5;" A mercury switch comprising a tubular metallic envelope, mercurytherein, a concentric vitreous tube within said envelope, said tubebeing closed at one point and having one end fused to said envelope,while the other end of said tube approaches an end of said envelope, andan inlead extending into said tube.

6. A mercury switch comprising a tubular metallic envelope, mercurytherein, a concentric vitreous tube within said envelope, said tubehaving one end fused to said envelope, while the other end of said tubeapproaches an end of said envelope, an inlead extending into said tube,said tube being fused to said inleadwhereby said tube serves both tohermetically seal said envelope and to retain a pool of said mercuryabout said inlead, and a refractory lining for the open end of saidtube, said lining having projections which engage said envelope wherebythe open end of said tube is rigidly supported.

7. A mercury switch comprising a sealed tubular envelope of vitreousmaterial, mercury therein, a concentric vitreous tube within saidenvelope, said tube having a closed end a portion of which is integralwith one end of said envelope, and an open end which approaches theopposite end of said envelope, said tube cooperating with said envelopeto entrap a pool of said mercury in said tube at all positions of saidswitch, two inleads sealed into said envelope, one of said inleadsextending into said tube through the portion thereof which is integralwith said envelope while the other extends into the annular spacebetween said tube and said envelope, said inleads terminating in contactrings inside of and outside .of said tube, respectively, the ring insideof said tube being thin and closely fitting said tube and extending .toa point which is at such a distance from the end of said tube that whensaid switch is tilted the entrapped mercury pool still extends beyondsaid ring toward theopen end of said tube after saidentrapped pool hasseparated from the mercury exterior to said tube, but near enough to theend of said tube to make contact .with said entrapped mercury when saidtube is vertical with the open end downward, the outer ring makingcontact with the main mercury body at all times that said body is mergedwith said entrapped pool, and an arc suppressing atmosphere in saidenvelope.

8. A mercury switch comprising a sealed tubular envelope, mercurytherein, a concentric vitreous tube within said envelope, one end ofsaid tube being closed while the other end thereof is open andapproaches an end of said envelope, whereby said tube cooperates withsaid envelope to entrap a pool of said mercury at all positions of saidswitch, an inlead sealed into said envolope and extending into saidtube, and an electrical conductor which makes contact with said mercuryat a point exterior of said tube whenever said switch is in such aposition that said mercury extends within the end of said tube, the openend of said tube being flared.

9. The method of producing a mercury switch which comprises forming aninlead with a contact sleeve thereon, inserting said sleeve in avitreous tube which it snugly fits, placing an enclosing envelope aboutsaid tube, and fusing said envelope and said tube together whilemaintaining said inlead and said envelope in predetermined relation,whereby said tube is maintained in the desired position within saidenvelope during the fusing operation.

10. The method of producing a mercury switch which comprises forming aninlead with a contact sleeve thereon, inserting said sleeve in avitreous tube which it snugly fits, placing an other sleeve with anattached inlead about said tube, placing an enclosing envelope aboutsaid tube and inleads, inserting a tubulation between said tube and saidenvelope, heating the end of said envelope and of said tube to thefusing temperature, and pinching them down onto said inleads whilemaintaining said inleads and said envelope in a predetermined relation.

11. The method of producing a mercury switch which comprises forming aninlead with a contact sleeve thereon, inserting said sleeve in avitreous tube which it snugly fits, placing another sleeve with anattached inlead about .said tube, placing an enclosing vitreous envelopethereof approaching the opposite end of said envelope, and two inleadssealed into said envelope, one of said inleads passing through theclosed end of said tube, and the other supporting the free end of saidtube, whereby said tube is supported by said inleads against lateraldisplacement at two separated points, said first mentioned inlead beinginsulated between said envelope and said tube.

13. A mercury switch comprising a tubular envelope, mercury therein, aconcentric vitreous tube within said envelope, one end of said tubebeing closed while the opposite'end thereof approaches an end of saidenvelope, an inlead extending into said tube, an'electrical conductor inthe rim of the open end of said envelope, said tube extending withinsaid envelope to a point near the opposite end thereof, and an inleadextending within said tube, said tube being hermetically sealed to saidinlead, whereby said tube serves to hermetically seal said envelope andto retain a quantity of mercury about said inlead.

FRANK MOOS.

